The invention relates to thermal ablation and, more particularly, to a thermal ablation apparatus for use with an endoscope.
Thermal ablation of tissue can be performed to remove diseased tissue, such as precancerous or cancerous tissue. For example, thermal ablation has been used in the treatment of Barrett""s esophagus, which is a precancerous condition. Thermal ablation can also be performed to remove old tissue and to provide a new surface to support growth of new tissue. Typically, thermal ablation is performed by passing an electrode through a working channel of an endoscope, placing the electrode near the tissue region to be treated and applying radio-frequency (RF) energy to the electrode. An advantage of this technique is that the procedure can be performed under direct visualization. A disadvantage of this technique is that the diameter of the electrode is necessarily limited by the small diameter of the working channel of the endoscope. As a result, the electrode can only treat a small area of the tissue at a time.
In some precancerous conditions that may be treatable via thermal ablation, the area to be treated is relatively large with respect to the electrode, resulting in very long procedure times, irregular or incomplete ablation, and variations in the depth of the ablative effect. The inability to control sufficiently the depth of the ablation procedure can lead to charring or perforation of the tissue or a failure to reduce significantly the number of precancerous cells to a sufficiently low level.
Attempts have been made to provide large electrodes to overcome these limitations. For example, electrodes have been provided on expandable surfaces such as balloons. These apparatuses, however, have been limited to some extent by the diameter of the accessory channel of an endoscope.
In general, the invention relates to thermal ablation of a large tissue area. Thermal ablation apparatuses, according to the invention, are designed for use with an endoscope.
In one aspect, the invention features an apparatus for use with an endoscope which includes a housing and at least one electrode. The housing is removably attachable to a distal terminating end of the endoscope. The housing includes an outer surface and a cross-sectional area that is at least as large as a cross-sectional area of the distal terminating end of the endoscope. The electrode is supported by at least a portion of the outer surface of the housing. The electrode is capable of delivering energy to a tissue region inside a body to ablate the tissue region.
Embodiments of this aspect of the invention can include the following features.
In one embodiment, the housing comprises an insulator. For example, the housing can comprise a thermal insulator and/or an electrical insulator. At least a portion of the housing can be transparent. Examples of materials suitable for forming the housing include, but are not limited to, a ceramic material, a glass, and a polymeric material. The housing can be substantially ring-shaped. In another embodiment, the housing includes a distal end and a proximal end. The proximal end comprises an elastomeric material and is sized and shaped to slip over the distal terminating end of the endoscope.
In one embodiment, at least one electrode includes a pattern. For example, the pattern can comprise a row of linear elements or a helical pattern. The electrode can be monopolar or bipolar. The housing can include at least one groove and the electrode can be positioned in the groove. The apparatus can further include an electrical conduit in electrical communication with at least one electrode. For example, the electrical conduit can be a wire, a pair of twisted wires, or a coaxial conductor.
In another aspect, the invention features an apparatus for use with an endoscope which includes a sheath, a housing, and at least one electrode. The sheath includes a first channel for receiving the endoscope. The housing is attached to a distal end of the sheath. The housing includes an outer surface and a cross-sectional area at least as large as a cross-sectional area of a distal terminating end of the endoscope. The electrode is supported by at least a portion of the outer surface of the housing. The electrode is capable of delivering energy to a tissue region inside a body to ablate the tissue region.
Embodiments of this aspect of the invention can include the following features.
In one embodiment, the sheath further includes a second channel coextensive with the first channel. An electrical conduit is disposed in the second channel. The electrical conduit is in electrical communication with at least one electrode. In another embodiment, the sheath further includes a second channel coextensive with the first channel for receiving a fluid. The sheath can comprise polyethylene. The sheath can have a thickness in the range from about 0.015 inches to about 0.085 inches.
In another aspect, the invention features a medical apparatus which includes an endoscope, a housing, and at least one electrode. The endoscope terminates at a distal end. The housing is removably attachable to the distal end of the endoscope. The housing includes an outer surface and a cross-sectional area at least as large as a cross-sectional area of the distal end of the endoscope. The electrode is supported by at least a portion of the outer surface of the housing. The housing is capable of delivering energy to a tissue region inside a body to ablate the tissue region.
In another aspect, the invention features a medical apparatus which includes an endoscope, a sheath, and at least one electrode. The endoscope terminates at a distal end. The sheath comprises a channel for receiving the endoscope and a housing attached to a distal end of the sheath. The housing includes an outer surface and a cross-sectional area at least as large as a cross-sectional area of the distal end of the endoscope. The electrode is supported by at least a portion of the outer surface of the housing. The electrode is capable of delivering energy to a tissue region inside a body to ablate the tissue region.
In another aspect, the invention features a method of treating tissue in a body which includes the following steps. A housing is removably attached to a distal terminating end of an endoscope. The housing is removably attachable to the distal terminating end of an endoscope. The housing includes an outer surface supporting at least one electrode on at least a portion of the outer surface and a cross-sectional area at least as large as a cross-sectional area of the distal terminating end of the endoscope. The endoscope and the housing are inserted inside the body near a tissue region to be treated. Energy is applied to at least one electrode to treat the tissue region.
In one embodiment, at least one electrode is connected to a power source through an electrical conduit housed in a channel of the endoscope. In another embodiment, a housing comprising at least one aperture is attached to the distal terminating end of the endoscope and a fluid is provided to the tissue region through the aperture. The fluid can be a cooling fluid, a flushing fluid and/or a conductive fluid. In still another embodiment, the tissue region is illuminated and an optical property of the tissue region is detected.
In another aspect, the invention features a method of treating tissue in a body including the following steps. A sheath comprising a channel for receiving an endoscope and a housing attached to a distal end of the sheath is provided. The housing includes an outer surface supporting at least one electrode on at least a portion of the outer surface and a cross-sectional area at least as large as a cross-sectional area of a distal terminating end of the endoscope. An endoscope is inserted inside the channel of the sheath, such that the housing is positioned near the distal terminating end of the endoscope. The sheath and the endoscope are inserted inside the body near a tissue region to be treated. Energy is applied to at least one electrode to treat the tissue region.
In one embodiment, at least one electrode is connected to a power source through an electrical conduit housed in a second channel of the sheath. In another embodiment, energy is applied to the tissue region to ablate the tissue region.
In another aspect, the invention features a method of manufacturing an ablation apparatus including the following steps. A housing is provided. A slurry comprising a conductive material and a solution is also provided. The slurry is applied to at least a portion of a surface of the housing. The solution is removed from the slurry applied on the surface of the housing to form an electrode comprising the conductive material on the surface of the housing.
In one embodiment, a slurry including a conductive material is printed on the surface of the housing. In another embodiment, the slurry including a conductive material is applied to the housing by spraying, brushing or dipping the housing into the slurry.
In another embodiment, the slurry is heated to remove the solution and to melt or reflow the conductive material.
In yet another embodiment, a housing comprising at least one groove is provided. The solution in the slurry applied to the surface of the housing is removed to form the electrode in the groove of the housing.
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims.